Brown bag: properly retire speaker bundle (OS_VERSION="4")

The change to retire the speaker bundle was incomplete and therefore OS_VERSION 3 is useless, this release fixes the retirement of the speaker bundle and makes myhouse-image-core buildable again.

Retire speaker bundle (OS_VERSION="3")

Broken: the only change in this OS_VERSION is incomplete and thus the v3 release is broken, please use v4.

Make use of SWUPD_EMPTY_BUNDLES to retire the speaker bundle in favour of a more generic renderer bundle

Fixes and toolchain hardening (OS_VERSION = "2")

Adopt some new features in meta-swupd (SWUPD_FILE_BLACKLIST and BUNDLE_FEATURES) and make use of security_cflags to enable toolchain hardening.

Complete initial base OS (OS_VERSION = "1")

At this point we hope to have a complete enough base OS defined (as the os-core bundle) that we can rely on this set of metadata to provide a base build and utilise swupd on the target to perform all updates and feature additions (via bundles) moving forward.